Ignoring the facts that most carbonated drinks are not particularly good for you. The fact is we all drink them, whether by themselves or as mixers.
Between Coke v Pepsi I prefer coke. Thats just personal choice. However I will say that Pepsi Max is quite a nice drink. Like diet Pepsi, Pepsi Max has artificial sweeteners in it and is thus very low in calories. It does however taste more like regular pepsi than the diet version and hence is more palatable. I think it might be called Pepsi One in the US but am not very sure. The product also comes with lots of cool extreme sports related adds that probably add to its credibility rather than being associated as a diet drink.
I personally out of choice wouldn’t drink pepsi or diet pepsi but I will occasionally pick up a pepsi max.